Under a cellular mobile communication system, the location registration is needed in some cases in accordance with the movement of a mobile terminal (for example, see Non-Patent Literature 1). An example is that when there are first and second cells respectively corresponding to first and second mobile switching centers and a mobile terminal located in the first cell moves to the second cell (when moving from a cell to another cell), the above mobile terminal needs to perform the location registration. That is, when the mobile terminal moves over two mobile switching centers, the location registration is needed in the second cell, which is a new location.
Referring to FIG. 10, for example, when a mobile terminal 1 of a subscriber A located in the first cell, which is a previously located cell, moves to the second cell, which is a newly located cell (S11), the mobile terminal 1 of the subscriber A transmits a location registration signal (S12).
Upon receipt of the location registration signal transmitted from the mobile terminal 1, an MSC/VLR 10 corresponding to the newly located cell acquires authentication information about the subscriber A from an MSC/VLR 20 corresponding to the previously located cell (S13). Then, an authentication process is performed at the MSC/VLR 10. In addition, the MSC/VLR 10 is capable of identifying the MSC/VLR 20 corresponding to the first cell, which is the previously located cell, based upon information included in the location registration signal transmitted from the mobile terminal 1. Then, the MSC/VLR 10 outputs to the MSC/VLR 20 a request signal for acquiring the authentication information, and the MSC/VLR 20 transmits the authentication information as a reply signal to the request signal. In this manner, the MSC/VLR 10 is capable of acquiring the authentication information about the subscriber A.
Next, the MSC/VLR 20 transmits the location registration signal transmitted from the mobile terminal 1 to an HLR 30 (S14). As a result, the MSC/VLR 20 is capable of downloading subscriber information about the subscriber A from the HLR 30 (S15). Subsequently, the MSC/VLR 20 refers to the downloaded subscriber information, and controls an outgoing transmission and the like from the user.
It is to be noted, however, that the HLR 30 sometimes falls in a congestion state, when the mobile terminal is located in the cell corresponding to the MSC/VLR 20. The HLR in a congestion state means that the HLR apparatus itself is in a congestion state or a transmission path to reach the HLR is in a congestion state.
When the HLR 30 is in a congestion state, the MSC/VLR 20 refers to a subscriber class included in the subscriber information downloaded from the HLR 30, and performs restriction control as follows. Referring to FIG. 11, for example, the MSC/VLR 20 restricts the outgoing transmission from the mobile terminal 1 of the subscriber A having the subscriber class of “general user”. According to this restriction, when the mobile terminal 1 initiates an outgoing transmission (S21a), such an outgoing transmission is restricted by the MSC/VLR 10 (S22). Therefore, an incoming reception request signal is not transmitted to the HLR 30. Thus, the outgoing transmission is restricted.
On the other hand, the MSC/VLR 20 does not restrict the outgoing transmission from a mobile terminal 2 of a subscriber B having the subscriber class of “priority user”. For this reason, when the mobile terminal 2 initiates the outgoing transmission (S21b), the MSC/VLR 10 permits the outgoing transmission (S22), an access of the incoming reception request signal to the HLR 30 is permitted (S23), and the outgoing transmission process continues.
In this manner, when the HLR 30 is in a congestion state, the outgoing transmissions from some mobile terminals are restricted, whereas the outgoing transmissions from the other mobile terminals are permitted, depending on the content of the subscriber class.